General Chemistry
posted by Kim .
A 230.0mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.50M. What volume of solvent has evaporated from the 0.275 M solution?
a)42.2 mL
b)63.3 mL
c)187.8 mL
d)230 mL
e)272.2 mL

How many moles do you hae ini the original sample? That is M x L = 0.275 x 0.230 = ?
You still have that number of moles in the sample after heating.
M = moles/L. You know M and moles, solve for L in the sample. Subtract from 0.230L to find the amount evaporated. 
Use formula M1 x V1 = M2 x V2
V2 = M1xV1/M2
V2 = 0.275M x 0.230L/1.50M = 0.0422L need to convert back to ml
0.0422L x 1000L/1mL = 42.2mL
A is the answer